Fluvastatin sodium is known by its chemical name (±)-7-(3-(4-fluorophenyl)-1-(1-methylethyl)-1H-indol-2-yl)-3,5-dihydroxy-6-heptenoic acid monosodium salt. Fluvastatin sodium is a racemic mixture of the 3R, 5S- and 3S, 5R-dihydroxy enantiomers represented by the Formula I.

Fluvastatin sodium is a competitive inhibitor of HMG-CoA reductase, which is responsible for the conversion of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) to mevalonate, a precursor of sterols, including cholesterol. The inhibition of cholesterol biosynthesis reduces the cholesterol in hepatic cells, which stimulates the synthesis of LDL receptors and thereby increases the uptake of LDL particles. The end result of these biochemical processes is a reduction of the plasma cholesterol concentration.
Fluvastatin as well as its sodium salt are described in U.S. Pat. No. 4,739,073. In this patent Fluvastatin sodium is obtained by lyophilization and discloses the amorphous form, which is unsuitable for large-scale production as disclosed in the further literature.
U.S. Pat. No. 6,124,340, describes that lyophilization of Fluvastatin sodium as was performed in examples 6(b) and 8 of '073 patent yields a mixture of a crystalline form, designated as Form A and amorphous material. The estimated amount of Form A obtained by lyophilization as described by '340 patent is about 50% in the said mixture.
The '340 patent describes a new crystalline form designated as Form B. The crystalline Form B is obtained either by transformation of material containing Form A in a slurry of a mixture of an organic solvent and water, or by crystallization from an organic solvent and water mixture. This patent also describes that Form B is less hygroscopic than Form A or the amorphous form of the Fluvastatin sodium, which improves handling and storage of the compound.
U.S. Pat. No. 6,696,479 describes crystalline forms of Fluvastatin sodium hydrates designated as form C, D, E, and F. The water content of the forms ranges between 3 to 32%. The patent also describes a new process for the preparation of highly crystalline form of Fluvastatin sodium Form A. The new crystal forms of Fluvastatin sodium were obtained by storing the sample under atmosphere ranging between 20 and 90% relative humidity.
International Publication No. WO2004/096765A2 describes crystalline form of Fluvastatin sodium monohydrate depicted as BA. The water content ranges from 3 to 6%. Similarly International Publication No. WO2005/080332 discloses novel crystalline form of Fluvastatin sodium with characteristic PXRD peaks. The water content ranges from 1 to 8%.
U.S. Patent Application No. 2005032884, U.S. Patent Application No. 20050038114 and U.S. Patent Application No. US2005119342 disclose novel crystalline forms of Fluvastatin sodium, some of which are hydrates and solvates.
Objective of the present invention is to provide novel and stable polymorphic forms of Fluvastain sodium, which can effectively used for different pharmaceutical formulation. Further, the process for preparing said polymorphic forms is cost efficient and the produced polymorph is easy to handle and convenient to operate on commercial scale.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of examples thereof.